As depicted in FIG. 8, a heat exchanger fin used in a heat exchanger such as a room air conditioner has a plurality of collar-equipped through-holes 104 formed in a length direction of a thin metal plate 102 made of aluminum or the like. As depicted in the enlargement, a collar-equipped through-hole 104 of the heat exchanger fin 100 has a brimmed collar 108 of a predetermined height formed around a through-hole 106 formed in the thin metal plate 102. Such collar-equipped through-holes 104 enlarge the heat-transfer area for the heat exchanger pipes fitted into the through-holes 104 and are therefore capable of improving the heat exchanging efficiency of the heat exchanger.
In addition, in the heat exchanger fin 100 depicted in FIG. 8, to improve the heat exchanging efficiency, louvers or slits (referred to hereinafter simply as the “louvers 112”) are formed between the collar-equipped through-holes 104. As depicted in the enlargement, the louvers 112 are formed by bending the metal strip that has been cut into narrow widths in the up-down direction. Also, corner cut portions 110 that are cutaway portions are formed at a plurality of locations on the heat exchanger fin 100 to prevent contact between the heat exchanger fin 100 and other components provided near the installed location of the heat exchanger.
The heat exchanger fin 100 depicted in FIG. 8 is normally produced by having a plurality of heat exchanger fins simultaneously molded in parallel from a wide metal strip 120 depicted in FIG. 9.
The wide metal strip 120 first undergoes a burring process B that forms small holes to be used for the collar-equipped through-holes 104 through punch machining (burring) and the wide metal strip 120 in which the small holes have been formed is then subjected to an ironing process A that draws the peripheries of the punched out small holes to increase the diameters of the through-holes 106 while raising the heights of the collars 108 and a reflare process F that forms brim portions by bending the front ends of the collars 108. A louver machining process L that forms the louvers 112 is also carried out.
In this way, a plurality of collar-equipped through-hole rows, each of which is composed of a plurality of the louvers 112 and the collar-equipped through-holes 104 formed in the length direction of the wide metal strip 120, are formed in the width direction of the wide metal strip 120.
Next, after a punching process N in which the corner cut portions 110 formed in the side surfaces of the wide metal strip 120 and the punched-out portions 114 located between the collar-equipped through-hole rows are punched out, the wide metal strip 120 is cut by a cutter process S into separate collar-equipped through-hole rows to produce narrow metal strips 123. Next, the narrow metal strips 123 are cut into short strips by a cutting out process C to produce heat exchanger fins 100 like that depicted in FIG. 8.
The various processes that produce the heat exchanger fin 100 depicted in FIG. 8 are carried out by the manufacturing apparatus depicted in FIG. 10 (see for example Japanese Laid-Open Patent Publication No. H11-192600).
In the manufacturing apparatus depicted in FIG. 10, the wide metal strip 120 is wound in a coil in an uncoiler 202 and is pulled out via pinch rollers 204. Machining oil is applied by an oil applying apparatus 206 onto the wide metal strip 120 that has been pulled out and then the wide metal strip 120 is supplied to a mold 208 provided inside a press apparatus 200. Inside the mold 208, the collar-equipped through-holes 104, the louvers 112, the corner cut portions 110, and the punched-out portions 114 are formed in the wide metal strip 120.
In this way, the wide metal strip 120 in which the collar-equipped through-holes 104, the louvers 112, the corner cut portions 110, and the punched-out portions 114 have been formed is supplied to a cutter 210 and cut in the length direction to produce the narrow metal strips 123 before such narrow metal strips 123 are cut into short strips. The heat exchanger fins 100 depicted in FIG. 8 produced by such cutting into short strips are stored in a stacker 211.